Vasily Smyslov vs Lembit Oll

White to play and win
(Not my post, but taken from http://www.chessgames.com/perl/chessgame?gid=1127089&kpage=1)

Thanks to a quick trip in our time machine, we find ourselves in prehistoric Britain. Ugg is sitting on the floor of his semi-detached cave banging two rocks together.

Uggette, his thick browed wife, is smearing mammoth dung on her cheeks, dreaming of the day when someone will invent make-up. "Why don't you go out hunting sabre-tooth tigers like the other troglodytes?" she asks. "Or you could go stare at the shiny black obelisk again."

"Peace, peace, light of my life, sharer of my cave, mother of my children. I'm trying to invent fire."

She tuts scornfully. "You and your silly ideas. It'll never work. All you'll do is get bruised knuckles and the neighbours will complain about the noise."

Ugg keeps knocking the rocks together. "Yes, but, just think what we could do with fire! We could stay warm and snug in our cave. It would frighten away the wolves. Then we could move away from being hunter-gatherers and start farming. Oh, and that would give us time for civilization, an industrial revolution, the internet..."

Today's puzzle is about inspiration and perspiration. The inspiration is to spot that we need to kick the black king away from the white rook on e4. Then we can grab the black bishop on g5. So the move that we really want to make work is 29. g4+. If we can force the black king to retreat, our next move will be 30. fxg5.

Of course, the problem with 29. g4+ is that it leaves the Re4 en prise. But let's not abandon the idea just yet. Let's see if we can make it work.

The black king is now deep into our territory and we are close to weaving a mating net. We must stop black from running back to safety via d5 or having the time to grab g4 with either pawn or bishop so the next move has to be 30. Nf2+ and black's reply is forced: 30...Kxf4.

Now black's king is nearly stalemated, so that any check would produce mate. We just need to cover the g3 escape square. Our rook is no longer needed to guard the d file, so 31. Rg1 comes to mind. We are threatening Bd2# or if 31...e4 32. Nh3#

A spark flashes from the rocks in Ugg's hands. It lands in a pile of leaves and starts to smoulder. He quickly blows on it, and seconds later we have fire.

"See! I told you it would work," says Uggette. "Now hurry up and invent handbags, cappucino and Jimmy Choos."

Humanity is based on a little bit of "I wonder if..." and an awful lot of stubbornness as we try to make the initial idea work.